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Harvesting pressure on Asian freshwater turtles is severe, and dramatic population declines of these turtles are being driven by unsustainable collection for food markets, pet trade, and traditional Chinese medicine. Populations of big-headed turtle (Platysternon megacephalum) have declined substantially across its distribution, particularly in China, because of overcollection. To understand the effects of chronic harvesting pressure on big-headed turtle populations, we examined the effects of illegal harvesting on the demography of populations in Hong Kong, where some populations still exist. We used mark-recapture methods to compare demographic characteristics between sites with harvesting histories and one site in a fully protected area. Sites with a history of illegal turtle harvesting were characterized by the absence of large adults and skewed ratios of juveniles to adults, which may have negative implications for the long-term viability of populations. These sites also had lower densities of adults and smaller adult body sizes than the protected site. Given that populations throughout most of the species' range are heavily harvested and individuals are increasingly difficult to find in mainland China, the illegal collection of turtles from populations in Hong Kong may increase over time. Long-term monitoring of populations is essential to track effects of illegal collection, and increased patrolling is needed to help control illegal harvesting of populations, particularly in national parks. Because few, if any, other completely protected populations remain in the region, our data on an unharvested population of big-headed turtles serve as an important reference for assessing the negative consequences of harvesting on populations of stream turtles. Evidencia Demográfica de la Captura Ilegal de una Tortuga Asiática en Peligro [ABSTRACT FROM AUTHOR]

1. A total of 950 251 individuals of 157 turtle species were recorded during a 35-month survey of the turtle trade in Hong Kong, Shenzhen and Guangzhou, southern China. All but two of the 157 species were encountered in Hong Kong; Guangzhou ranked second in diversity (113 species) and Shenzhen third (89 species). Together, these turtles made up around 60% of the global chelonian fauna; 124 (′80%) of them were freshwater turtles. 2. Seventy-two globally threatened species were traded in southern China during the survey: 13 classified by the IUCN as critically endangered (CE), 29 as endangered (EN), and 30 as vulnerable (VU). Thirteen species listed on CITES Appendix I and 64 species on Appendix II, as well as eight species nationally protected in China, were traded. 3. The majority of species traded had natural ranges that included China and neighbouring Southeast Asian countries, or Southeast Asian countries other than China. These non-Chinese Asian turtles (primarily Bataguridae) constituted around two-thirds of the 77 species in the food trade, and turtles sold as food accounted for 73% of individuals encountered during the survey. Most species sold as food were also traded as traditional Chinese medicine, and nearly all turtles (155 of 157 species) were sold as pets. Eighty-one species were traded only as pets. 4. Large numbers of Cuora galbinifrons (CE; CITES-Il) were traded (> 15000 individuals) and even greater quantities (>210000 individuals) of C. amboinensis (VU; CITES-Il), as were significant numbers of other CR, EN and VU batagurids. Observed levels of exploitation of wild populations appeared unsustainable. 5. Enforcement of relevant CITES regulations during the survey seemed limited and globally threatened Asian species remained in trade in Hong Kong without the relevant licences. Trade within China is not subject to CITES, but could be regulated by enforcement of existing national laws and expansion of protected-species lists. [ABSTRACT FROM AUTHOR]

The demand for fish maw (i.e., dried swim bladder) has apparently intensified during the past decades in Hong Kong and mainland China; currently, maw has similar annual import volumes but far higher mean unit values than other important seafood delicacies like shark fins and sea cucumber. Escalated demand for seafood delicacies can significantly contribute to the depletion of marine resources; yet a comprehensive understanding of maw value and the fisheries that supply it is lacking. We review available information on eight important maw-supplying species in major and largely undocumented source countries to examine the susceptibility and exposure of fisheries to the maw trade, which primarily serves Chinese demand. Comparing ex-vessel price ratios of maw to flesh (USD/kg), the overall mean price of maw can be as much as 72 times higher (range between 12:1 and 8389:1). Catch, price and export trends demonstrate that demand for maw is likely intensifying in countries already supplying it, shifting or expanding to new species, and emerging in new regions. We find that most maw-supplying species are under high fishing pressure, poorly or not protected. Those that yield the highest maw prices exhibit spawning aggregations, making them exceptionally vulnerable to overexploitation. While management interventions are needed to sustain fishery resources and capture economic benefits, their effectiveness will be challenged by the high value of maw. [ABSTRACT FROM AUTHOR]